Fire-resisting doors with expandable seal means including a thermal conductor



Feb. 11, 1969 R. GAETH ET AL 3,426,491

FIRE-RESISTING DOORS WITH EXPANDABLE SEAL MEANS INCLUDING A THERMALCONDUCTOR Filed March 28, 1967 F|G.3 I,

INVENTORS RUDOLF GAETH FRITZ STASTNY RUDOLF BREU FRIEDHELM GAERTNERATT'YS United States Patent U.S. Cl. 52204 10 Claims Int. Cl. E061)1/06, 5/10; E04b 1/76 ABSTRACT OF THE DISCLOSURE Fire-resisting doorsconsist of an incombustible material or are at least combined therewithand have, at the edges and/or in the door frame rabbet, layers ofmaterials which expand under heat and which in the case of fire, fillout the gap between the edge of the door and the door frame withfoamlike substances which offer certain resistance to the spread of fireat these particularly endangered places.

The present invention relates to the provision of such expandablematerials along the edges of the door.

The edges and corners of fire-resisting closures, for examplefire-resisting doors, are particularly weak spots through which flamesand smoke first penetrate. Fireresisting wooden doors first burn throughat these spots, so that the unexposed face of the door ignites althoughthe door itself is still substantially intact and would offer adequateresistance. This problem occurs particularly on the hinge side of thefire-resisting doors. These problems are not so serious when the firebreaks out on the side of the door away from the hinge because the edgesof the door are substantially protected by the door frame.

To overcome this disadvantage it is known that grooved depressions maybe provided along the edges of the door and/ or in the door frame andthat they may be filled with an expandable material. This materialconsists substantially of an organic binder, for example polyvinylacetate, and an expanding agent which disengages gas when heated, forexample dicyanodiamide or ammonium phosphate. When subjected to hightemperatures, such as occur when a fire breaks out, this materialexpands between the edge of the door and the door frame. The foam thusformed has only slight mechanical stability however and consequentlyoffers only limited resistance to the spread of the fire. Anotherdisadvantage is that the expandable material introduced into the groovescannot be covered to protect it from mechanical damage because otherwiseit would not expand sufficiently and above all not quickly enough in theevent of fire.

It is also known that articles may be protected from the effects of afire by means of alkali metal silicate especially sodium and potassiumsilicate sheets which contain water and glass fibers. These sheets havethe property, owing to the high temperature to which they are subjectedin the event of fire, of expanding to a foamed layer which has very goodmechanical and thermal stability.

These alkali metal silicate sheets have, with reference to the anhydrousalkali metal silicate contained therein, a water content of 20 to 70% byweight, preferably 40 to 60% by weight, and fibers in an amount of to40% by weight, preferably to 25% by weight. Glass fibers are stated tobe particularly suitable fibers, and especially fibers having athickness of from about 0.1 to 0.3 cm. are favorable which consist ofmany individual filaments whose diameter is from 5 to 15 microns. Thesefibers are known as chopped strands.

We have now found that the fire resistance of fire-reslsting doors isconsiderably improved by providing, along the edges and/or in the doorframe rabbet, strips which consist of at least one layer of alkali metalsilicate containing fibers and water and a material having good thermalconductivity, said strips being arranged with their narrower sideperpendicular to the face of the door.

Fire-resisting doors whose edges or door frame rabbet have been providedonly with strips of alkali metal silicates containing fibers and waterhave greater fire resistance as compared with doors whose edges havebeen provided with organic compounds which expand when heated.Surprisingly however this resistance may be considerably increased bycombining the strips containing alkali metal silicate with strips of amaterial having good thermal conductivity. This measure of combining thealkali silicate strips with a material having good thermal conductivitywould have led one to expect exactly the opposite effect, namely thatthe fire resistance of a fireresisting door would be reduced.

In the event of fire, the alkali metal silicate strips containing fibersand water form a mechanically stable foam which fills out the frame andthe door so that the door becomes firmly jammed in the frame.Penetration of heat, flames and smoke is thus prevented even when thefire continues for a prolonged period. In the case of wooden doors thereis less warping. Doors even remain inv their frames when, as a result ofthe stiles charring, the hinges are no longer anchored in the door.

The strips containing alkali metal silicate and the strips of materialhaving good thermal conductivity have a width which advantageously isabout equal to the width of the edge of the door. The thickness of thestrips containing the alkali metal silicate is advantageously about 1.5to 2.5 mm. The thickness of the material having good thermalconductivity depends on the thermal conductivity of the particularmaterial chosen. For example in the case of materials having goodthermal conductivity such as copper and aluminum, the latter beingparticularly suitable, thicknesses of 0.1 to 0.3 mm. are sufiicient,whereas with materials having poorer thermal conductivity, e.g. iron,correspondingly greater thicknesses must be used. By materials havinggood thermal conductivity we mean those which have a high heat transfercoefiicient of at least 0.09 cal./cm. sec. C., which are thermallystable and whose melting point is above 500 C. The strips areadvantageously arranged along the edge of the door in such a way thatfirst there is a strip containing alkali metal silicate and then a stripof material having good thermal conductivity. On these strips, forexample, another strip containing alkali metal silicate may be laid. Itis also possible to place a metal strip on either side of the stripcontaining the alkali metal silicate. Such a combination reactsparticularly quickly under the action of fire. This combination ofstrips may be covered with protective layers, for example of woodveneer, bonded asbestos sheets or plastics without the effect beinglost. Obviously it is also possible to use layers consisting of morethan three strips instead of layers consisting of only three strips. Thefire retarding effect is thus further enhanced at the corners and edges.The number of layers chosen depends therefore on the fire-retardingeffect to be achieved.

In order to ensure increased resistance to the passage of heat and flameat the corners of the door, which constitute a particularly weak spot,it is advantageous to chamfer the corners and to apply a plurality oflayers of strips containing alkali metal silicate and strips of athermally conducting material in such a way that the chamfer is filledup with these strips and the foam expands in the direction of thecorner.

The invention will "be further described with reference to theaccompanying drawings in which FIGURE 1 is a horizontal section andFIGURE 2 is a vertical section of a door. FIGURE 3 is a horizontalsection of a door, a door frame and the adjacent brickwork. The sameparts are indicated by the same reference numerals in all the figures.

In FIGURE 1, 1 indicates a face veneer and 2 indicates the facing whichadvantageously consists of an incombustible, thermally insulatingmaterial, for example a sheet of alkali metal silicate containing fibersand water. 3 and 3a indicate the fire-resisting edging member consistingof strips of alkali metal silicate containing fibers and water andstrips of material having good thermal conductivity. 4 indicates anouter layer, for example of hardwood, asbestos cement sheets orplastics. 5 indicates the framework of the door, for example of gluedstrips. 6 indicates the panel. As more clearly shown in FIGURE 2, thecorners of the stiles of the door are chamfered and the chamfer isfilled up with a plurality of layers of strips of alkali metal silicatecontaining fibers and water 3 alternating with strips of material havinggood thermal conductivity, for example aluminum foil, 3a.

In FIGURE 3, 7 indicates brickword and 8 a door frame of steel or wood.9 indicates the door. A strip 3 of alkali metal silicate containingfibers and water and a metal foil 3a are applied to the door frame 8,the metal foil being covered with a protective layer 10.

The invention is further illustrated by the following examples.

EXAMPLE 1 The door has a total thickness of 54 mm., a height of 1,990mm. and a width of 986 mm. The framework, which is 35 mm. thick andconsists of theree spruce strips, each 30 mm. in width, glued together,is provided with a twice glued lock reinforcement and a horizontal rail.The frame and the hardboard connecting members are covered on both sideswith the following layers:

On a veneer having a thickness of 1.5 mm. there is a sheet 1.5 mm. inthickness of sodium silicate having a water content of 30% by weight anda ratio of Na O:SiO of 1:1.3. 0.5 mm. gauge wire cloth with a mesh of 25mm. is embedded in the sheet. It also contains 120 g./sq. m. of choppedglass strands and 50 g./sq. m. of cane sugar. The sheet is coated oneither side with 100 g./sq. m. of an epoxide resin. This sheet isfollowed by another wood veneer having a thickness of 1.5 mm. and thenagain by a sodium silicate sheet. The final layer is a cross-grainedwood veneer 1.5 mm. thick. The whole five layers are firmly gluedtogether with a phenol-resorcinol-formaldehyde condensation resin at atemperature of 100 C. This covering is glued onto the framework of thedoor and further secured with twenty penetrating steel clips, 55 mm. inwidth. The four corners of the framework of the door are chamfered sothat both edges are shortened by 40 mm. The chamfer is filled up byalternate layers of fourteen strips about 1.5 mm. in thickness of sodiumsilicate containing fibers and water and thirteen strips of aluminumfoil having a thickness of 0.1 mm.

The edges of the door are provided all round with a fire-resistingedging member about 50 mm. in width. This member, viewed in thedirection of the door, of a wood veneer 0.8 mm. thick, a sodium silicatestrip 1.5 mm. thick whose composition is like that of the abovementionedsheet and which is coated on both sides with epoxide resin, an aluminumfoil having a thickness of 0.1 mm., another strip of sodium silicate andanother wood veneer having a thickness of 0.8 mm. To this fireresistingedging member, at the sides and bottom, a 5 mm. edging member of oak isapplied and an edging member of asbestos cement is applied to the top ofthe Temperature in fire chamber C.)

Duration in minutes The door is firmly jammed in the frame.

N 0 change.

End of test, a small hole has formed at the upper left-hand corner.

EXAMPLE 2 Two doors, each having a total thickness of 40 mm. areconsrtucted, as described in Example 1, from wooden strips having athickness of 30 mm., hardboard members and wood veneer faces 1.5 mm.thick, 2. sheet of sodium silicate 1.5 mm. thick and as defined inExample 1, and a wooden veneer 1.5 mm. thick.

(a) A fire-resisting edging member of a strip of sodium silicate 1.5 mm.thick is applied to the edges of one door. The upper chamfered corner ofthe door is filled up with fourteen superposed sodium silicate strips.

(b) A fire-resisting edging member of a strip of sodium silicate 1.5 mm.thick and an aluminum foil 0.1 mm. thick is applied to the edges of theother door. The similarly chamfered corner of this door is filled upwith alternately superposed layers of fourteen sodium silicate stripsand thirteen strips of 0.1 mm. aluminum foil.

An edging member of oak which has been rebated 10 mm. wide and 27 mm.deep, is applied to the fire-resisting edging members in both cases.

The two doors are fitted into commercial steel frames in an oven. In afire test carried out according to DIN 4102 (1940) the following resultsare obtined by exposing the hinge side of the doors to the flames:

After the test has proceeded about twenty-five minutes, a. hole appearsat each of the upper corners of door (a), whereas this is not observedin the case of door (b) until after about forty minutes.

We claim:

1. A fire-resisting doorway comprising a door frame and a door therein,and at least one of the edge portions of said door and the door framehaving mounted thereon superposed strips of (a) at least one layer ofalkali metal silicate containing fibers and water and (b) at least onestrip of a thermally stable, heat conductive material having a heattransfer coefficient of at least 0.09 cal./cm. sec. C. and a meltingpoint above 500 to provide a heat expandable combination adapted to fillthe gap between the edges of the door and the door frame in cases offire, the strips being arranged with their narrower side perpendicularto the face of the door.

2. A fire-resisting door with its door frame-opposing edge portionshaving superposed strips of (a) at least one layer of alkali metalsilicate containing fibers and water and (b) at least one strip of athermally stable, heat conductive material having a heat transfercoefiicient of at least 0.09 cal. cm./ sec. C. and a melting point above500 C. to provide a heat expandable combination adapted to fill the gapbetween the edges of the door and the door frame in cases of fire, thestrips being arranged with their narrower side perpendicular to the faceof the door.

3. A fire-resisting door comprising a door body having at least onechamfered corner which is filled out by a plurality of diagonallydisposed, alternate strips of heat foamable alkali metal silicatecontaining fibers and water and strips of thermally stable, heatconductive material having a heat transfer coeificient of at least 0.09cal./ cm. sec. C. and a melting point above 500 C., the strips beingarranged with their narrower side perpendicular to the face of the door.

4. A fire-resisting door frame having a door frame rabbet andcharacterized by said rabbet having superposed strips of (a) at leastone layer of alkali metal silicate containing fibers and water and (b)at least one strip of a thermally stable, heat conductive materialhaving a heat transfer coeflic ient of at least 0.09 cal./cm. sec. C.and a melting point above 500 C. to provide a heat expandablecombination adapted to fill the gap between the edges of the door andthe door frame in cases of fire, the strips being arranged with theirnarrower side perpendicular to the face of the door.

5. A fire-resisting doorway as claimed in claim 1 wherein the layers ofsaid alkali metal silicate have a thickness of 1.5 to 2.5 mm.

6. A fire-resisting door as claimed in claim 2 wherein the layers ofsaid alkali metal silicate have a thickness of 1.5 to 2.5 mm.

7. A fire-resisting door frame as claimed in claim 4 wherein the layersof said alkali metal silicate have a thickness of 1.5 to 2.5 mm.

8. A fire-resisting doorway as claimed in claim 1 6 wherein said heatconductive material is copper foil, aluminum foil, or a thin iron strip.

9. A fire-resisting door as claimed in claim 3 wherein said heatconductive material is copper foil, aluminum foil, or a thin iron strip.

10. A fire-resisting door frame as claimed in claim 4 wherein said heatconductive material is copper foil, aluminum foil, or a thin iron strip.

References Cited UNITED STATES PATENTS 2,910,739 11/ 1959 Snitker 49-5043,254,592 6/ 1966 Chase 49-504 3,255,559 6/1966 Gaeth et a1 52-2323,274,734 9/ 1966 Davis 52--623 X FOREIGN PATENTS 644,500 7/1962 Canada.

20 ALFRED G. PERHAM, Primary Examiner.

US. Cl. X.R.

